1. Field of the Invention
The invention relates to a technical field of a controller for a hybrid vehicle.
2. Description of Related Art
There is known that torque pulsation occurs in a crankshaft of an internal combustion engine. In a vehicle configuration in which the crankshaft is coupled to a drive shaft coupled to drive wheels, the torque pulsation is transmitted to the drive shaft, causing vibrations and noise (hereinafter, referred to as “vibration noise” where appropriate) of the vehicle. Japanese Patent Application Publication No. 2010-023790 (JP 2010-023790 A) describes that, in order to suppress such vibrations and noise, a pulsation component of torque is calculated, and a pulsation torque for cancelling this pulsation component is output from an electric motor.
In a technical field different from suppression of noise and vibrations due to torque pulsation, when no torque is applied to a gear coupled to a drive shaft in a vehicle configuration including a differential gear mechanism between an internal combustion engine and an electric motor, the gear is pressed by adding pressing torque, thus suppressing noise due to looseness (for example, a play, such as backlash) of the gear mechanism (see Japanese Patent Application Publication No. 2012-148645 (JP 2012-148645 A)).
There is also a technique for changing an operation line of an internal combustion engine between an operation line for suppressing vibration noise and an operation line for fuel economy on the basis of an operating state of the internal combustion engine (see Japanese Patent Application Publication No. 2010-264796 (JP 2010-264796 A)). JP 2010-264796 A also describes that torque for cancelling torque pulsation is output from an electric motor in the case where the operation line for fuel economy is used.